1. Field of the Invention
The present invention relates generally to the fields of pathogenic fungi and immunology. More particularly, the invention provides compositions of peptides and genetic constructs expressing the peptides and methods of using such compositions in generating effective immune responses against pathogenic Coccidioides spp. fungi, such as C. immitis. The compositions, combinations and methods of the invention are thus useful in prophylactic and therapeutic applications to combat coccidioidomycosis and Valty Fever, the diseases caused by Coccidioides spp. infection.
2. Description of Related Art
Coccidioides spp., including C. immitis and C. posadasii, are pathogenic fungi endemic to the southwestern United States, including parts of Texas, California, Nevada, Utah, Arizona and New Mexico, parts of Mexico and in other countries in Central and South America. C. immitis was first described, and is now becoming known as the Californian population. The C. posadasii species was recently defined, and was previously recognized as the non-Californian population of C. immitis (Fisher et al., 2002).
The Coccidioides spp. organisms grow in the soil and, following winter rains, produce arthroconidia. Infection of mammals generally occurs in the summer months when hot, dry conditions favor inhalation of Coccidioides spp. arthroconidia spread by wind or by physical disturbance of infected soil. Coccidioides spp. infection causes disease in dogs and cats, amongst other mammals.
In humans, infection by C. immitis and C. posadasii leads to coccidioidomycosis, also known as the disease Valley Fever (or San Joaquin Valley Fever). An estimated 100,000 persons are infected each year (Stevens, 1995). The disease can range from a primary, asymptomatic infection to a disseminated process involving virtually any organ in the body, with the exception of the gastrointestinal tract. High risk groups include persons of Asian, Black, or Hispanic ancestry, pregnant females, older persons, and those who are immunocompromised. The morbidity and mortality of the disease causes problems for those living in the relevant geographical areas. The need for effective immunization strategies is further emphasized by increased travel and urbanization of the endemic areas.
Certain methods are available to treat coccidioidomycosis in mammals, including systemic anti-fungal therapies. In humans, the available treatment methods are limited by problems of patient tolerance and drug resistance. The development of preventative measures is preferred over methods to treat the infection once it has occurred. Unfortunately, although certain immunization strategies have been explored, there remains in the art a need to identify biological components that generate effective immune responses against Coccidioides spp. The identification of smaller immunogenic components and/or those that elicit cell-mediated immune responses would be a particular advance in this area.